Visual tracking of auditory stimuli.

A white noise sound stimulus was emitted successively in an anechoic chamber across 24 loudspeakers equally spaced in the horizontal plane in a semicircle with diameter of 11 ft. Eye movements produced by each of 20 normal-hearing young adults in the center of this arc who tracked the sound at 10 different velocities (15--180 degrees/sec) were recorded with standard ENG methods. During each rotating cycle of the stimulus the eyes were able to follow the sound with discrete saccades, but did not produce nystagmic-like movements. Increased stimulus velocity resulted in (1) diminution of the amplitude of the tracking cycles, (2) decrease in the number of saccades, and (3) increase in the average velocity of the eye. Ss performed better with lights on than off. The additional quantitative findings from the present study further indicate the limitation in the ability of human Ss to localize a moving acoustic source in space.